How to leaves fresh for Monarch butterfly eggs? I accidentally cut off the stem they were on :(

alright I just did something very stupid. I decided to cut a stem off my swamp milkweed without checking for monarch eggs first. Because I’ve yet to see any adults actually hanging around the plants (and only one adult at all any time recently), but I know monarchs like fresh leaves, and the swamp milkweed already has a bunch of oleander aphids on them, so I figured I’d cut off a few inches where the aphids are the worst, the plant would grow new leaves, and the monarchs would lay eggs on the new leaves!

Well. Only after I cut the stem off and set it down did I realize there were two monarch eggs on it :/

so my question now is, is there anything I can do to keep the two leaves the eggs are on fresh / hydrated long enough for the eggs to hatch? Once they hatch I’d put them back on the same plant, but I don’t know how long it takes the eggs to hatch…

Would sticking the stem in a bottle of water (with plastic wrap around the stem so they can’t fall in somehow) close enough to the main plant work, that way they could crawl to the rest of the plant on their own?

Sticking the leaves in a plastic container with a wet paper towel, or something?

Needless to say I will never be cutting off milkweed stems without checking first…

Edit: I’ve put the stem in a bottle of water with a ziplock bag with a small hole poked in it, with the bag taped in place, but if anyone has better suggestions please let me know!

Edit 2: Update!

Both monarchs have safely hatched, and have been put back on the main plant! :)

Here’s their observations:

1: https://www.inaturalist.org/observations/130161994
2: https://www.inaturalist.org/observations/130161995

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Just putting the stem in water is enough. They’re only eggs for a few days and don’t move very much after they hatch. Putting the leaves on a damp paper towel works but not as well, especially with swamp milkweed since it dries out and shrivels up pretty quickly.

After they hatch you can use a very fine haired small artist’s type paintbrush and kind of turn it next to the tiny larva which will pick them up gently and then do the reverse to roll them onto a new leaf. I’ve also just cut around them and placed the tiny piece of old leaf on a fresh leaf and usually crawl off that way.

It’s also possible to move eggs too which I’ve done at times. You need a steady hand though, because it can be a bit fiddly. You can use something very thin and sharp like a razor blade and carefully scrape the surface of the leaf under the egg, lifting it off. Then use a drop of water with that artists paintbrush to sort of glue it onto another leaf.

I have common milkweed planted in several areas of my garden, but it spreads around a lot where I don’t want it too. So I often have to pull out stems. I always check it for eggs and larva to transfer to another plant before I toss it in the compost bin.

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Okay, that’s good to know! I’ll keep it in the bottle of water then, since my hands are not steady at all.

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Could you graft the cut-off to an existing stem?

Does grafting work with swamp milkweed? The stems on the one I cut off and the main plant a very thin, not even the size of a pen.

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I’m not sure, maybe someone with more horticulture/gardening experience could comment? I’d maybe try grafting it to an existing node and support both with twine and stakes until the graft takes.

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If the leaves are still attached to a stem, you could put it in water. Alternatively, you could put the leaves on a moist paper towel inside a plastic container to keep them from drying out too much and watch for changes. The egg will get a dark spot (the caterpillar’s head visible through the translucent shell) right before they hatch out. Once the caterpillars hatch, they’ll eat their egg shell first before starting to chew on the leaves.

You could gently coax them from the cut leaves onto fresh ones but there’s a risk of injuring the tiny early instars. The paintbrush trick works, or if you are patient just hold the old leaf next to a fresh one and let them crawl over. They indeed like fresh leaves, so chances are they’ll take the opportunity to voluntarily leave the old one for greener pastures. You could also tie/clip the old leaf with the egg/caterpillar on it to the plant and they’ll eventually find their way up the stem to the fresh leaves.

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Yeah I figured once they hatch I’ll either hold the leaf next to one on the plant, or use a paper clip or something to attach it. It’s been three hours since I put the stem in water, and the leaves are still upright and hydrated, (plus now it’s raining) so I think this will work well!

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Update: The monarchs have both hatched, and are now safely back on the main plant :)

Here’s their observations!

1: https://www.inaturalist.org/observations/130161994
2: https://www.inaturalist.org/observations/130161995

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Awesome! What did you end up doing to keep the cut-off alive until they hatched?

I had a little soda bottle I filled with water, then taped a plastic bag over it upside down, with a little tear in the plastic to hold the stem upright and to stop anything from falling into the water. Then I propped the bottle up in the plant pot the milkweed was in :)

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